The packaging of hybrid integrated circuits continues to evolve in response to downsizing demands common among a number of industries. Those skilled in the art are familiar with redistributed chip packaging (RCP) processes employed in conjunction with artificial, or reconstituted wafers, to form hybrid integrated circuits in relatively thin (planar) wafer level packages. In the medical device industry, the construction of IMD's can benefit from such electronics packaging.
FIG. 1 is a schematic showing a typical IMD 100, which is suitable for cardiac monitoring and/or therapy delivery, implanted at a subcutaneous pectoral site in a patient 102. FIG. 1 illustrates IMD 100 including a hermetically sealed and biocompatible canister 104, for example, formed from a Titanium alloy, which houses a power source and electronic circuitry, and one or more electrical leads 106, which are coupled to the circuitry and extend distally from canister 104, through the venous system 110 and into the heart 108 of patient 102, for example, the right ventricle (RV). Those skilled in the art understand that the one or more leads 106 preferably include sensing and therapy delivery electrodes, which are coupled to the IMD circuitry via one or more lead connectors that terminate elongate insulated conductors of the electrodes, at a proximal end of lead(s) 106; the one or more lead connectors are plugged into a connector module 105, which is mounted on canister 104, to make electrical contact with the contained IMD circuitry via hermetically sealed feedthroughs.
IMD 100 may function as an implantable cardioverter defibrillator (ICD) to detect atrial and/or ventricular fibrillation and, in response to the detection, to deliver high voltage shock therapy in order to terminate the fibrillation. FIG. 2 is a simplified circuit diagram for an exemplary voltage generator portion of ICD circuitry. FIG. 2 illustrates a flyback transformer 240 connected across terminals of a power source 220, a switch 232 connected in series with a primary winding of transformer 240, and a diode 234 connected in series with a secondary winding of transformer 240 across a load, which includes a capacitor element 239 connected by another switch 236 to heart 108, for example, via one or more leads 106 (FIG. 1). FIG. 2 further illustrates a sense circuit 260 that monitors voltage of capacitor element 239, and a controller 210 that receives a signal from the sense circuit 260 to deliver energy from power source 220 when the voltage of capacitor element 239 is below a predetermined threshold. Those skilled in the art will appreciate that a cycling of switch 232 causes transformer 240 to incrementally charge capacitor element 239 to generate voltage on the order of 750 volts or more, so that, when switch 236 is closed, defibrillation shock energy, for example, at a level in the range of 5-40 Joules may be delivered to heart 108
In the past, transformer 240 would be constructed as a conventional type of flyback transformer from components that are physically separate from one another and from other electrical components of the ICD circuitry, for example, primary and secondary windings formed around a toroid-shaped magnetic core. Because these components of the conventional transformer take up a relatively large amount of space within canister 104, recent efforts to reduce an overall size of canister 104, for a more comfortable implant, have focused on reducing the size of flyback transformers that are employed for charging ICD capacitors. Commonly-assigned U.S. Pat. No. 7,167,074 describes the construction of planar flyback transformers, for physical integration of the transformer with other elements of ICD circuitry, wherein primary and secondary windings are embedded between opposing sides of a printed circuit board (PCB) to which a planar magnetic core is mounted (i.e. E-shaped core with legs/feet extending through openings in the PCB such that the windings are disposed thereabout). Although the embodiments of planar flyback transformers that are described in the '074 Patent can reduce the amount of space taken up by a transformer, such as transformer 240 within canister 104, there is still a need for improved assemblies of planar flyback transformers, as well as other passive components that include windings (i.e. antennas for telemetry modules), which can be integrated into wafer level packages of hybrid integrated circuits, for further downsizing of IMD's.